Converting kilotons to feet is not an accurate or even a logical conversion, but it did give a sense of scale and the dramatic difference in sizes of each of the tests, particularly the difference between the first atomic bomb and the hydrogen bombs that would be developed soon after.

The markers began at zero feet from the projection wall - which displayed a continuous loop of explosions. So, a 5 kt test would be 5 feet from the screen, a 10 kt test would be marked 10 feet from the screen, and so on.

For example, the Hiroshima test (they still refer to it as a “test” in government documents) would be about 15 feet from the projection wall. To illustrate how much larger tests had grown a little over a decade later, the largest test (by the USSR), would have been closer to five miles from the projection wall.

The difference in the size of the tests is alarming.